Mold closing mechanism



MOLD CLOS INC: MECHANISM Filed A ril -14, 1938 a 7 N INVE TOR l' l /I 2 v fi 4 .10 a HANS GAS TR W ATT VS.

Patented Oct. 7, 1941 UNITED STATES PATENT "OFFICE 2.25am om cnosmc MECHANISM I Hans Gastrow, Zerbs t, Anhalt, Germany Application April 14,'19as,'sernl No. 202,109 I In Germany April 15, 193':

3 Claims.

produce pressure holding the mold closed during the molding operation. v

As is known, the pressure required to hold the mold closed in the injection'molding of plastic materials assumes very considerable values, e. g. 50,000 kgs. and more. It, as is usual, an electric motor is employed for driving the mold closing mechanism, then taking account of the transmission arrangement interposed between .the motor and the mold closing' mechanism this motor must produce a torque corresponding to the mold closing pressure. As the magnitude 0! the torque corresponds with the size or the motor it has been necessary with the transmisslon means hitherto known to make the motor comparatively large although only a very small power is required for the actual opening and closing movement.

Fig. 2 is a side view of the mold closing mechanism in part section.

Fig. 3- is a plan view corresponding to Fig. 2.

In the drawing the stationary mold section is indicated at I and the movable mold section at 2. The moldsectlons are guided on two rails 3 and ,4, which are bolted to the table] or the cast housing. 6.

Movement is imparted to the movable mold section 2 by means of a toggle linkage I. The link 1 is connected with a shaft 0 which is' mounted in the rails 2, 4 and the bearing members 3a,. The links 'I and 8 are connected to-" gether by the shaft III. A further shaft ll serves for n;ounting the link 8 at the movable mold section The toggle linkage of-a further toggle linkage l2, l3. The link I3 is also mounted on the shaft III. The manner in which the lever i 2 is mounted and driven is shown in Fig. 1. Mounted in the housing 0 is a cup-shaped casting H, which accommodates the electric motor H from which the drive is derived. The driving shaft I0 01 the motor llv It is an object of the invention to provide' 988868 o l h the bottom IT ifl casting transmission means for use between the motor and the mold section which is moved by the mo-' tor and so constructed that large closing pres,

sures can be produced .with, a comparatively small motor. Forthis purpose the drive of the movable mold section is eifected by means of a double toggle mechanism, the toggle link which is driven by the motor being connected therewith by way or a planetary gearing. This gearg consists of two internally toothed rings arranged side by side and having a slightly difler nt number of teeth. One toothed ring is stationary and the other is connected with the drive motor shaft and in so doing roll over the thed rings. As a result there is a rotation or e movable toothed ring corresponding to the erence in thelnumber of teeth in the two thed rings.

h number of teeth in each toothed ring with i y a small difference in the numbersoi teeth, t is possible to obtain very high transmission atios;

Oneembodiment-of the invention will ribed by way of example with-reference'to the companying drawing, in which:

Fig. 1 shows a section through the mechanism perating the toggle linkage. 1

By providing a comparatively- .5 bedeen link or the toggle linkage. Both toothed rings are engaged by toothed'wheels which rotate with 4 the housing 0 opposite the motor II is provided with a web l9 provided with-an integral flange 20. The lever I2 is mounted in this flange 20. The lever -l2 consists of a cup-shaped housing 2| with two-integral bearing straps 22, 23 accommodating a shaft 24 which serves for the pivotal connection of the lever I2 with the link internally toothed rings 26, 2'l.- In the embodi- 0 ment shown both these rings have the same in-' ternal diameter.

The ring 26 is secured to the lever l2 by means of bolts 20 and the ring 21 is secured by bolts 29 to the base ll of the casting ll. The rings have different numbers of teeth 0 being of equal nodule. For example, the ring 21 may have eigthy-one teeth and the ring 20 may have seventy-eight teeth.

Keyed on the shaft i0 isia casting or bearing member of- H-shaped cross section. Jour- 0 nailed in this casting 30 are pairs of gear wheels ll which engage with the toothed wheels. Any desired number of pairs of wheels can be provided. when the shaft l6 rotates, the wheels ll roll on the stationary toothed ring 21. If the toothed rings 26 and 21 have the same number I, 0 is actuated by means.

of teeth the toothed ring 26 also would be stationary, but as it has a difierent number of teeth there is a slow rotation of this toothed ring with corresponding movement of the lever I2.

By making the lever l2 in the form of a housing it is possible for the gearing to be enclosed in an oil-tight and dust-tight manner. To ensure that this result is obtained, a packing 32 is inserted between the stationary toothed ring 21 and the housing portion 2| of the movable lever l2. Inaddition a packing 33 is provided where the shaft it passes through the base ll of the cup-shaped casting i4. i

To limit the movement of the toggle linkage l2, li a stop is provided on the housing 6. This stop consists of a circular eccentrically mounted disc 43 which can be secured in any desired position by means of a bolt 44. Due to the eccentric mounting of thedisc 43, it is thus possible to adjust the stop in a simple way. A ring 42 carried on the shaft 24 engages the stop 43. To cushion the impact when the ring 42 encounters the stop 43, a rubber ring 45 is inserted between the ring 42 and the shaft 24. v

I claim:

1. A mold closing mechanism for a pair of relatively movable mold sections comprising a motor, a shaft driven by said motor, two pairs of toothed wheels, means secured to said shaft whereby the toothed wheels revolve in diametrically opposite pairs about the axis of the shaft during the rotation of the latter, an internally toothed ring in mesh with one pair of wheels and rigidly mounted on said base, asecond internally toothed ring with a different number of teeth mounted adjacent the first-mentioned toothed ring and in mesh with the other pair of wheels, said rings being of equal nodule, a toggle link formed at one end as a housing accommodating and rigidly connected with said second-mentioned ring and embracing said first ring, and a second toggle link transmitting the movement of the second-mentioned ring and the first-mentioned toggle link to effect the opening and closing of the movable mold section.

2. A mold closing mechanism for a pair of relatively movable mold sections, comprising a toggle linkage transmitting a movement to eifect the opening and closing of the movable mold section, a planetary gearing imparting the movement to one of the toggle links, means for driving said gearing, and an eccentric stop adjustably secured in a fixed position for limiting the movement of said link associated with the planetary gearing.

3. A mold closing mechanism for a pair of relatively movable mold sections, comprising a toggle linkage transmitting a movement to effect the opening and closing of the movable mold section, a planetary gearing imparting the movement to one of the toggle links, a motor for driving said gearing, a stop for limiting the movement of said link associated with the planetary gearing, a pin provided on said link for co-operation with said stop, a resilient cushioning ring surrounding the pin, and a stop-engaging ring .carried around said cushion.

HANS GASTROW. 

